Drills routinely comprise a base body extending in the axial direction along an axis of rotation. On the end surface, the drill comprises a drill face with cutting edges, which usually extend to cutting corners, which define a nominal radius of the drill. Flutes for removing the chips produced during drilling are usually incorporated into the base body. Starting from the cutting corner, a minor cutting edge usually extends along the respective flute.
There are basically different types of drills, such as one-piece drills, in particular solid carbide drills, or even modular drills, in which a cutting element, such as a drill tip, or even cutting plates are usually reversibly exchangeably mounted on a base body.
For a dimensional stability as high as possible of a drill hole produced using the drill, a reliable guidance and true-running accuracy of the drill is of particular importance. In order to reliably produce a drill hole with a defined diameter, drills usually comprise guide chamfers and additionally often times also support chamfers, which are formed on a rear surface of the drill. “Rear surface” generally refers to the part of the drill between two consecutive flutes in the circumferential direction. The rear surface therefore extends from a leading flute to a trailing flute in relation to a direction of rotation of the drill during operation.
At the edge of the rear surface toward the leading flute, the so-called guide chamfer is usually formed, which extends along the flute. This edge toward the leading flute can be designed as a minor cutting edge.
Toward the trailing flute, an additional support chamfer is often times arranged on the rear surface. Both the guide chamfer and typically also the support chamfer extend in the radial direction to the nominal radius and in the direction of rotation usually in an arc shape over a few angular degrees.
The guide and support chamfers however necessarily result in a friction between the respective chamfer and the drill hole wall, which in particular leads to a heating and hence a thermal load and thus to an early wear of the drill.